Dustmen at last on street work uninterrupted (3-4)
I believe the answer is:
non-stop
'uninterrupted' is the definition.
(I've seen this before)
'dustmen at last on street work' is the wordplay.
'at last' suggests the final letters.
'street' becomes 'st' (abbreviation).
'work' becomes 'op' (abbreviation for opus).
The last letter of 'dustmen' is 'n'.
'n'+'on'+'st'+'op'='NON-STOP'
(Other definitions for non-stop that I've seen before include "Ceaseless" , "continuously" , "Round-the-clock" , "Unceasing" , "Going straight from A to B" .)